1. Field of the Invention
The present invention relates to a fluid ejection head for ejecting fluid by thermal energy and a fluid ejection recording apparatus using this fluid ejection head. This invention can be applicable to an apparatus for ejecting fluid for various and is purposes especially preferable for use in a printer and its application apparatus.
2. Description of the Prior Art
Many technical papers and articles on fluid ejecting technologies using thermal energy are found in the field of recording information on a recording medium. In recording information by ejecting fluid by using thermal energy, for example, an electric resistance element is used as means for generating energy for ejecting fluid. The electric resistance element defines a heat applying face which directly or indirectly applies thermal energy to fluid. By applying thermal energy to fluid in a short period of time, film boiling occurs in fluid and a bubble caused by this film boiling grows. And hence, a pressure wave induced by this bubble growing pushes fluid outside an ejection orifice so as to record images on a recording media.
In the recording method by ejecting ink fluid, as a plurality of ejection orifices for ejecting fluid for recording can be arranged in high density, expected are various advantages such as attaining the high resolution images on a recording medium and making the recording head in a small-sized element.
However, in trying to arrange a plurality of ejection orifices with fine intervals, it is required that the size of the cross section of a fluid paths should be taken to be small enough. In this case, as the impedance and the inertance of the fluid path may be high, the refill time after ejecting ink fluid, the time defined for refilling fresh ink fluid again in the fluid path from the supply port and forming a meniscus near the ejection orifice is getting longer, and this creates an obstacle for attaining high speed recording.
In Japanese Patent Application Laid-open No. 204,352/1985, disclosed is an ink jet recording head where a fluid resistor for reducing the amount of fluid flowing back to a supply port side is installed in the fluid path between the electric resistance element and the supply port in order to make fluid ejection operations stable. In this prior art, it may be difficult to fabricate an ink jet recording head having a complex structure including the fluid resistor and to control the fluid flow precisely, and distinguished advantages cannot be expected.
In Japanese Patent Application Laid-open No. 87,356/1989, disclosed is an ink jet recording head where the cross-section of the fluid path in the perpendicular direction to the fluid flow is increased as it goes to the ejection orifice in order to use kinetic energy of the above mentioned bubble efficiently to be converted for ejecting ink fluid. And furthermore, in Japanese Patent Application Laid-open No. 195,050/1989, which corresponds to U.S. Pat. No. 4,752,787, an embodiment of a fluid path is disclosed where the height of the fluid path near the thermal energy supplying part, that is, the electric resistance element, is relatively higher than other parts of the fluid path so that the fluid path may not be plugged by the bubbles, which is also one embodiment of the invention disclosed in Japanese Patent Application Laid-open No. 139,970/1981, which corresponds to U.S. Pat. No. 4,410,899. In case, however, only a single objective is set forth it does not further increase combinational effects.
U.S. Pat. No. 4,752,787, discloses a structure of the fluid path, the cross-section of which increases in the direction toward the common fluid reservoir in order to increase refilling performances, the relative difference of fluid impedance increases and the location of developing the bubble by thermal energy is shifted to the common fluid reservoir. This contradicts the objective of making the fluid path shorter.
In Japanese Patent Application Publication No. 59,672/1987 which corresponds to U.S. Pat. No. 4,417,251, a wall covering around the electric resistance element generating thermal energy is formed by a hard layer made of photosensitive resin materials. This invention advances the reduction of friction loss between the wall and the fluid.
In Japanese Patent Application Laid-open No. 109,669/1980, which corresponds to U.S. Pat. No. 4,410,899 disclosed is use of an element for generating thermal energy and that large-grained sludges in ink fluid are trapped by forming a coupling part with its cross-section less than or equal to the cross-section of the ejection orifice in the fluid path. In this invention, many modifications of shapes of the fluid path are described in detail, but the relative position of the electric resistance element in the fluid path is not described at all. According to drawings of this gazette, it may be understood that the electric resistance element may be located in the region of the fluid path where the cross-section is reduced toward the ejection orifice.
So far, there are many prior arts which disclose the structure of the fluid path and the layout of heat generation elements such as a heater or an electric resistance element, but none of them refers to altering the fluid ejection operations.